Actually there is only one season where there was a significant change in scoring and that was PItt they went up 9 points in scoring and then down 12 points the year after.
NIU year before 31.2 to32.2 to 35.1
IU 23.5 to 27.2 to 21.8
NIU 38 to 30.3 to 38.6
Wisconsin 44.1 to 28.9 to 34.8
NC St 27 to 30.2 to 27
PItt 26.1 to 35.2 to 23.9
LSU 28.3 to 27.2 to 33.4
The first is scoring before Canada the next is with Canada and third is year after
If you really look there is really no significant change.
So, he actually improved scoring at NIU, IU, NC State, and PITT.
You protect yourself by saying no 'significant' improvement. But in more cases, there was improvement, including when he was at IU.
And guess what - the drop at IU after he left - when Wilson came in - there was a SIGNIFICANT drop.
So, you can play with numbers and, to support your argument, ignore when he actually improved things (but not 'significant' in your words); but there's a reason football people think he's pretty good and actually put their money where their mouths are and hire him - unlike football fans sitting in their recliner who can state whatever opinion they want.